Small angle x-ray scattering studies will be carried out on 16S RNA from the 30S subunit of E. coli ribosomes. In addition the scattering from partially reconstituted 30S subunits will be studied. By comparing the scattering curves from the 16S RNA, the 16S RNA plus 1 protein, 16S RNA plus 2 proteins, etc., we hope to determine something about the configurational changes that take place during reconstitution. If the circumstances are favorable we may be able to determine the separation between pairs of proteins as they are added during assembly.